Electrodeposited crumpled MoS₂ nanoflakes for asymmetric supercapacitor

Transition metal chalcogenides are gaining attraction in the emerging energy-storing field owing to their captivating properties. Molybdenum disulfide (MoS₂) was deposited on Ni foam by using a one-step electrodeposition method. X-ray diffraction study showed that the deposited MoS₂ was amorphous, and X-ray photoelectron spectroscopy confirms the presence of Mo and S in the 4⁺ and 2⁺ oxidation states. Different nanostructures were observed by varying the deposition time, and MoS₂ deposited for 300 s has an interconnected crumpled-nanoflake structure. The electrochemical performance of MoS₂ electrodes was investigated between 0.2 and 1 V vs. SCE potential in 1M Na₂SO₄ electrolyte and the interconnected crumpled-nanoflake structure showed a maximum areal capacitance of 416.9 mFcm⁻² at a current density of 1 mAcm⁻². The charge storage kinetics of electrodes showed the diffusion-controlled contribution is greater than the capacitive-controlled contribution for MS-300 electrode. Also capacitive-controlled contribution is proportional to the scan rates. An asymmetric device was assembled using activated carbon and MoS₂ as negative and positive electrodes respectively, which exhibited an areal capacitance of 277.3 mFcm⁻² and energy density of 0.15 mWhcm⁻² at 5.33 mWcm⁻² power density measured at 3 mAcm⁻² current density. Furthermore, 90.1% cyclability and excellent coulombic efficiency measured up to 3000 cycles were observed for an asymmetric device. These results depict the potential candidature of MoS₂ and MoS₂//AC devices as an emerging energy storing devices.